The invention relates to a method and apparatus for packaging an inflatable airbag cushion for use in transportation vehicles.
It is well known to utilize inflatable air bag cushions to provide protection to vehicle occupants during a collision event. Such air bag cushions are deployed rapidly by the introduction of inflation gas upon the occurrence of predetermined vehicle conditions such as deceleration exceeding a certain level. In order to provide a cushioning barrier to the occupant to be protected, it is generally desired that the air bag unfold from a stored position in a rapid manner upon the introduction of the inflation gas. Thus, it is required that the air bag be folded in a manner to facilitate such rapid deployment. In addition, it is generally desirable for the folded air bag cushion to be stored in a relatively compact stored arrangement prior to activation.
Various equipment has been utilized to fold air bag cushions into compact arrangements which occupy little space in a stored condition prior to deployment but which nonetheless expand rapidly to an operable inflated condition upon introduction of the inflation gas. One folding apparatus which has been utilized has made use of paddles to create a series of substantially regular fan-type folds in the air bag cushion. An alternative apparatus is disclosed in U.S. Pat. No. 6,260,330 to Borowski et al. (incorporated by reference) which utilizes a walled housing in which the air bag cushion is folded by a number of cycles of increasing and decreasing pressure to achieve a desired folding arrangement. Still another folding apparatus is illustrated and described in U.S. Pat. No. 6,248,052 to Kleeberger et al. (incorporated by reference) wherein the air bag cushion is folded in a substantially irregular chaotic arrangement within an air bag module covering element.
In accordance with one potentially preferred embodiment and practice of the present invention, advantages and alternatives are provided over known folding practices and equipment by providing a folding method and apparatus for compacting an air bag cushion in a substantially chaotic folded arrangement within a cover element for an air bag module utilizing a controlled vacuum and/or enhanced pressurization within the interior of the air bag cushion during the folding operation and a moveable surrounding containment tunnel which may be moved into an operative position surrounding the air bag cushion above the cover element while also providing a channel for directing the air bag cushion into the cover element during the folding operation.
According to one potentially preferred folding practice, an air bag cover element is loaded into a nest support while an air bag cushion with attached base plate is loaded onto a moveable holding fixture arranged in opposing relation to the supported air bag cover element. A ram cylinder connected to a vacuum/compressor source is introduced through a central opening within the air bag base plate and into the interior of the air bag cushion to apply vacuum and/or pressurizing forces during selected periods of the folding operation. A vacuum is applied to collect the air bag cushion around the ram cylinder. A hollow containment tunnel in the form of a rodless cylinder or the like is thereafter lowered over the holding fixture in surrounding relation to the air bag cushion. The base plate holding fixture and containment tunnel are moved towards an opening in a working plate located between the holding fixture and the air bag cover element. The containment tunnel establishes a travel conduit through the working plate and feeding into the air bag cover element. The base plate holding fixture and ram cylinder continue to move through the containment tunnel thereby compressing the air bag cushion within the cover element until the air bag base plate engages attachment structures such as hook elements extending away from the walls of the air bag cover. The holding fixture then releases the air bag cushion and base plate assembly and the components of the folding apparatus return to their starting position.
In accordance with one potentially preferred practice, the ram cylinder may be pressed forward against the closed end of the air bag cushion prior to introduction of any vacuum so as to promote the substantially uniform distribution of air bag material around the ram cylinder. The closed end of the air bag is thereby held in tension along a folding axis defined by the extended ram cylinder during the folding process so that it defines a center about which the air bag cushion may be folded. The moveable containment tunnel further facilitates the maintenance of this generally central arrangement.
Due to the relative displacement of the various components within the folding apparatus, the loading of the air bag cushion and attached base plate and the air bag cover element may be performed in a highly efficient and reproducible manner. Further advantages and features of the present invention will become apparent through reference to the accompanying drawings and detailed description of the preferred embodiment of the invention as set forth below.